Listen and Learn
Learning by listening to information as we sleep has long been a mainstay of science fiction—and wishful thinking—but a new study suggests the idea may not be so farfetched. What we hear during deep sleep can strengthen memories of information learned while awake.

Researchers at Northwestern University taught 12 subjects to associate 50 images with specific positions on a computer screen. When the subjects saw each image, they also heard a matching noise—for instance, on seeing a cat, they heard a meow. Then the subjects each took a 60- to 80-minute nap. While they were in slow-wave sleep (a deep-sleep phase marked by slow electrical oscillations in the brain), the researchers played the noises that matched 25 of the images they had been studying. On waking, the subjects were asked to perform the same image-matching task. They were much better at correctly placing the images for which they had heard the noise cues while they napped. The participants reported they had no idea sounds had been played during their naps, and when asked to guess which sound cues they heard, they were just as likely to pick the wrong ones as the right ones.

“We were certainly surprised,” says co-author Ken Paller, director of the Cognitive Neuroscience Program at Northwestern, explaining that he did not expect such strong results. Although previous research has suggested that sleep alone can help consolidate memories, this study is the first to show that sound cues can strengthen specific spatial memories. Paller and his colleagues will next explore how long these effects last and whether aural cues can strengthen other types of memories as well. Until then, go ahead and play those French tapes while you snooze—it couldn’t hurt.

A Movie and a Nap
Practice makes perfect, but can simply watching help, too? Yes, if you sleep on it right away, reports a study from the Netherlands Institute for Neuroscience. Ysbrand Van der Werf and his colleagues tracked how well people learned to tap their fingers in a specific sequence—without any practice. Watching a video of the finger-tapping task led to faster and more accurate first attempts at the target sequence only when study participants slept within 12 hours of the video, before being tested. The finding not only points to a promising way to augment practicing when learning a new physical skill, it could also help people regain skills after injuries such as stroke.